Reticle constructions and photo-processing methods

ABSTRACT

Some embodiments include a reticle which includes first pattern features and second pattern features. A first optimal dose of actinic radiation is associated with the first pattern features and a second optimal dose of the actinic radiation is associated with the second pattern features. The second pattern features are larger than the first pattern features. Each of the second pattern features has a configuration which includes a central region laterally surrounded by an outer region, with the central region being of different opacity than the outer region. The configurations of the second pattern features balance the second optimal dose of the actinic radiation to be within about 5% of the first optimal dose of the actinic radiation. Some embodiments include photo-processing methods.

RELATED PATENT DATA

This application claims priority to and the benefit of U.S. ProvisionalPatent Application Ser. No. 63/071,263, filed Aug. 27, 2020, thedisclosure of which is incorporated herein by reference.

TECHNICAL FIELD

Reticle constructions, photo-processing methods, integrated circuitfabrication (e.g., fabrication of NAND memory).

BACKGROUND

Photolithography is commonly used during formation of integratedcircuits on semiconductor wafers. More specifically, a form of radiantenergy is passed through a radiation-patterning tool and onto aradiation-sensitive material associated with a semiconductor wafer. Theradiant energy can be referred to as actinic energy, and may be light inthe ultraviolet (UV) range, deep UV range, etc. The radiation-sensitivematerial is a photo-imagable material, such as, for example,photoresist.

The radiation-patterning tool may be referred to as a photomask or areticle. The term “photomask” is traditionally understood to refer tomasks which define a pattern for an entirety of a wafer, and the term“reticle” is traditionally understood to refer to a patterning toolwhich defines a pattern for only a portion of a wafer. However, theterms “photomask” (or more generally “mask”) and “reticle” arefrequently used interchangeably in modern parlance, so that either termcan refer to a radiation-patterning tool that encompasses either aportion or an entirety of a wafer. For purposes of interpreting thisdisclosure and the claims that follow, the term “reticle” is to beunderstood to be generic to traditional photomasks and reticles unlessexpressly stated otherwise.

Some of the applications discussed in the embodiments below pertain tomemory fabrication (e.g., NAND memory fabrication). FIG. 1 shows a blockdiagram of a prior art device 1000 which includes a memory array 1002having a plurality of memory cells 1003 arranged in rows and columnsalong with access lines 1004 (e.g., wordlines to conduct signals WL0through WLm) and first data lines 1006 (e.g., bitlines to conductsignals BL0 through BLn). Access lines 1004 and first data lines 1006may be used to transfer information to and from the memory cells 1003. Arow decoder 1007 and a column decoder 1008 decode address signals A0through AX on address lines 1009 to determine which ones of the memorycells 1003 are to be accessed. A sense amplifier circuit 1015 operatesto determine the values of information read from the memory cells 1003.An I/O circuit 1017 transfers values of information between the memoryarray 1002 and input/output (I/O) lines 1005. Signals DQ0 through DQN onthe I/O lines 1005 can represent values of information read from or tobe written into the memory cells 1003. Other devices can communicatewith the device 1000 through the I/O lines 1005, the address lines 1009,or the control lines 1020. A memory control unit 1018 is used to controlmemory operations to be performed on the memory cells 1003, and utilizessignals on the control lines 1020. The device 1000 can receive supplyvoltage signals Vcc and Vss on a first supply line 1030 and a secondsupply line 1032, respectively. The device 1000 includes a selectcircuit 1040 and an input/output (I/O) circuit 1017. The select circuit1040 can respond, via the I/O circuit 1017, to signals CSEL1 throughCSELn to select signals on the first data lines 1006 and the second datalines 1013 that can represent the values of information to be read fromor to be programmed into the memory cells 1003. The column decoder 1008can selectively activate the CSEL1 through CSELn signals based on the A0through AX address signals on the address lines 1009. The select circuit1040 can select the signals on the first data lines 1006 and the seconddata lines 1013 to provide communication between the memory array 1002and the I/O circuit 1017 during read and programming operations.

The memory array 1002 of FIG. 1 may be a NAND memory array, and FIG. 2shows a block diagram of a three-dimensional NAND memory device 200which may be utilized for the memory array 1002 of FIG. 1 . The device200 comprises a plurality of strings of charge-storage devices. In afirst direction (Z-Z′), each string of charge-storage devices maycomprise, for example, thirty-two charge-storage devices stacked overone another with each charge-storage device corresponding to one of, forexample, thirty-two tiers (e.g., Tier0-Tier31). The charge-storagedevices of a respective string may share a common channel region, suchas one formed in a respective pillar of semiconductor material (e.g.,polysilicon) about which the string of charge-storage devices is formed.In a second direction (X-X′), each first group of, for example, sixteenfirst groups of the plurality of strings may comprise, for example,eight strings sharing a plurality (e.g., thirty-two) of access lines(i.e., “global control gate (CG) lines”, also known as wordlines, WLs).Each of the access lines may couple the charge-storage devices within atier. The charge-storage devices coupled by the same access line (andthus corresponding to the same tier) may be logically grouped into, forexample, two pages, such as P0/P32, P1/P33, P2/P34 and so on, when eachcharge-storage device comprises a cell capable of storing two bits ofinformation. In a third direction (Y-Y′), each second group of, forexample, eight second groups of the plurality of strings, may comprisesixteen strings coupled by a corresponding one of eight data lines. Thesize of a memory block may comprise 1,024 pages and total about 16 MB(e.g., 16 WLs×32 tiers×2 bits=1,024 pages/block, block size=1,024pages×16 KB/page=16 MB). The number of the strings, tiers, access lines,data lines, first groups, second groups and/or pages may be greater orsmaller than those shown in FIG. 2 .

FIG. 3 shows a cross-sectional view of a memory block 300 of the 3D NANDmemory device 200 of FIG. 2 in an X-X′ direction, including fifteenstrings of charge-storage devices in one of the sixteen first groups ofstrings described with respect to FIG. 2 . The plurality of strings ofthe memory block 300 may be grouped into a plurality of subsets 310,320, 330 (e.g., tile columns), such as tile column_(I), tile column_(j)and tile column_(K), with each subset (e.g., tile column) comprising a“partial block” of the memory block 300. A global drain-side select gate(SGD) line 340 may be coupled to the SGDs of the plurality of strings.For example, the global SGD line 340 may be coupled to a plurality(e.g., three) of sub-SGD lines 342, 344, 346 with each sub-SGD linecorresponding to a respective subset (e.g., tile column), via acorresponding one of a plurality (e.g., three) of sub-SGD drivers 332,334, 336. Each of the sub-SGD drivers 332, 334, 336 may concurrentlycouple or cut off the SGDs of the strings of a corresponding partialblock (e.g., tile column) independently of those of other partialblocks. A global source-side select gate (SGS) line 360 may be coupledto the SGSs of the plurality of strings. For example, the global SGSline 360 may be coupled to a plurality of sub-SGS lines 362, 364, 366with each sub-SGS line corresponding to the respective subset (e.g.,tile column), via a corresponding one of a plurality of sub-SGS drivers322, 324, 326. Each of the sub-SGS drivers 322, 324, 326 mayconcurrently couple or cut off the SGSs of the strings of acorresponding partial block (e.g., tile column) independently of thoseof other partial blocks. A global access line (e.g., a global CG line)350 may couple the charge-storage devices corresponding to therespective tier of each of the plurality of strings. Each global CG line(e.g., the global CG line 350) may be coupled to a plurality ofsub-access lines (e.g., sub-CG lines) 352, 354, 356 via a correspondingone of a plurality of sub-string drivers 312, 314 and 316. Each of thesub-string drivers may concurrently couple or cut off the charge-storagedevices corresponding to the respective partial block and/or tierindependently of those of other partial blocks and/or other tiers. Thecharge-storage devices corresponding to the respective subset (e.g.,partial block) and the respective tier may comprise a “partial tier”(e.g., a single “tile”) of charge-storage devices. The stringscorresponding to the respective subset (e.g., partial block) may becoupled to a corresponding one of sub-sources 372, 374 and 376 (e.g.,“tile source”) with each sub-source being coupled to a respective powersource.

The NAND memory device 200 is alternatively described with reference toa schematic illustration of FIG. 4 .

The memory array 200 includes wordlines 202 ₁ to 202 _(N), and bitlines228 ₁ to 228 _(M).

The memory array 200 also includes NAND strings 206 ₁ to 206 _(M). EachNAND string includes charge-storage transistors 208 ₁ to 208 _(N). Thecharge-storage transistors may use floating gate material (e.g.,polysilicon) to store charge, or may use charge-trapping material (suchas, for example, silicon nitride, metallic nanodots, etc.) to storecharge.

The charge-storage transistors 208 are located at intersections ofwordlines 202 and strings 206. The charge-storage transistors 208represent non-volatile memory cells for storage of data. Thecharge-storage transistors 208 of each NAND string 206 are connected inseries source-to-drain between a source-select device (e.g., source-sideselect gate, SGS) 210 and a drain-select device (e.g., drain-side selectgate, SGD) 212. Each source-select device 210 is located at anintersection of a string 206 and a source-select line 214, while eachdrain-select device 212 is located at an intersection of a string 206and a drain-select line 215. The select devices 210 and 212 may be anysuitable access devices, and are generically illustrated with boxes inFIG. 4 .

A source of each source-select device 210 is connected to a commonsource line 216. The drain of each source-select device 210 is connectedto the source of the first charge-storage transistor 208 of thecorresponding NAND string 206. For example, the drain of source-selectdevice 210 ₁ is connected to the source of charge-storage transistor 208₁ of the corresponding NAND string 206 ₁. The source-select devices 210are connected to source-select line 214.

The drain of each drain-select device 212 is connected to a bitline(i.e., digit line) 228 at a drain contact. For example, the drain ofdrain-select device 212 ₁ is connected to the bitline 228 ₁. The sourceof each drain-select device 212 is connected to the drain of the lastcharge-storage transistor 208 of the corresponding NAND string 206. Forexample, the source of drain-select device 212 ₁ is connected to thedrain of charge-storage transistor 208 _(N) of the corresponding NANDstring 206 ₁.

The charge-storage transistors 208 include a source 230, a drain 232, acharge-storage region 234, and a control gate 236. The charge-storagetransistors 208 have their control gates 236 coupled to a wordline 202.A column of the charge-storage transistors 208 is those transistorswithin a NAND string 206 coupled to a given bitline 228. A row of thecharge-storage transistors 208 is those transistors commonly coupled toa given wordline 202.

It is often desired to simultaneously pattern features of differentsizes during fabrication of integrated circuitry (e.g., integratedmemory). However, such patterning is difficult at least in part due todifficulties in forming reticles suitable for effectively utilizing asingle dose of actinic radiation to pattern features of different sizes.It is desired to develop new reticle configurations, and new methods ofutilizing such reticle configurations for photo-processing duringfabrication of integrated circuitry.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of a prior art memory device having amemory array with memory cells.

FIG. 2 shows a schematic diagram of a prior art memory array in the formof a 3D NAND memory device.

FIG. 3 shows a cross-sectional view of the prior art 3D NAND memorydevice of FIG. 2 in an X-X′ direction.

FIG. 4 is a schematic diagram of a prior art NAND memory array.

FIG. 5 shows diagrammatic top views of a photoimageable material (leftside of the figure), and a pattern formed within the photoimageablematerial (right side of the figure).

FIG. 6 is a diagrammatic side view of an example apparatus configuredfor a photo-processing.

FIG. 7 is a diagrammatic top view of example regions of an examplereticle.

FIGS. 8 and 9 a graphical views of relationships of intensity versusdistance for actinic radiation passing through the example regions ofthe example reticle of FIG. 7 .

FIG. 10 shows one of the regions of FIG. 7 modified to alter therelationship of intensity versus distance for radiation passing throughsaid one of the regions, and shows graphical relationships of intensityversus distance for the actinic radiation passing through said one ofthe regions before and after the modification.

FIG. 11 is a flow-chart description of an example process of an exampleembodiment.

FIG. 12 shows diagrammatic top views of a photoimageable material (leftside of the figure), and a reticle (right side of the figure). Thereticle may be utilized to form an illustrated pattern within thephotoimageable material.

FIGS. 13 and 13A are a diagrammatic top view and a cross-sectional sideview, respectively, of an example pattern feature (patterning feature)of an example reticle. The view of FIG. 13A is along the line A-A ofFIG. 13 .

FIGS. 14 and 14A are a diagrammatic top view and a cross-sectional sideview, respectively, of an example pattern feature (patterning feature)of an example reticle. The view of FIG. 14A is along the line A-A ofFIG. 14 .

FIGS. 15A-15D are diagrammatic top views of example pattern features(patterning features) of example reticles.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Some embodiments include reticles having first and second patterningfeatures, with the second patterning features being larger than thefirst patterning features. The second patterning features may beconfigured to balance an optimal dose of actinic radiation associatedtherewith so that the optimal dose of the actinic radiation associatedwith the second features is about the same as that associated with thefirst features, even though the first patterning features are smallerthan the second patterning features. Some embodiments includephoto-processing (photo-patterning) methods. Example embodiments aredescribed with reference to FIGS. 5-15 .

Referring to FIG. 5 , an assembly 10 is shown at an initial processstage “A” on the left side of the figure, and at a subsequent processstage “B” on the right side of the figure.

The assembly 10 at the process stage “A” includes photoimageablematerial 12 formed over an underlying substrate 14 (with regions of thesubstrate 14 being visible at the process stage “B”). The assembly 10includes a pair of memory array regions 16 a and 16 b, and includesanother region 18 between the memory array regions 16 a and 16 b. Theregions 16 a and 16 b eventually include memory cells. The memory cellsmay be NAND memory cells which are formed along the vertically-extendingchannel regions of the type described above with reference to FIG. 2 ,with the memory cells along a common channel corresponding to a stringof the memory cells (e.g., a NAND string). Each of the memory cells ofan individual string may be within one of the tiers 0-31 of FIG. 2 . Theglobal control gate (CG) lines (wordlines) of FIG. 2 extend along thetiers and laterally between the memory cells, with the wordlines alsoextending to row decoder circuitry as described above with reference toFIG. 1 .

In some embodiments, the openings 20 of the process stage “B” areutilized to pattern locations for vertically-extendingchannel-material-pillars within the memory arrays 16 a and 16 b.

In some embodiments, the region 18 may correspond to an interconnectregion (for instance, may include a staircase region), and may beutilized for forming connections to the wordlines. Such electricalconnections may extend to the row decoder circuitry and to associatedwordline driver circuitry. Alternately and/or additionally,interconnects formed within the region 18 may extend to other componentsassociated with NAND memory, such as, for example, source structures,SGS devices, etc. Alternatively and/or additionally, structuresanalogous to functional interconnects may be formed within the region 18and may be utilized for structural support only rather than forelectrical connections (i.e., at least some of the structures formedwithin the region 18 may correspond to so-called “dummy” structures).

In the illustrated embodiment of FIG. 5 , the interconnect region 18 maybe considered to be proximate to the memory array regions 16 a and 16 b,and to be between the illustrated memory array regions.

The photoimageable material 12 is exposed to patterned actinic radiationto form first openings 20 within the memory array regions 16 a and 16 b,and to form second openings 22 within the intermediate region 18. Insome embodiments, the first openings 20 may be considered to correspondto first target features formed within the photoimageable material 12,and the second openings 22 may be considered to correspond to secondtarget features formed within the photoimageable material. Notably, thesecond target features 22 are much smaller than the first targetfeatures 20. In some embodiments, each of the first target features 20may occupy an area which is at least about 50% bigger than an areaoccupied by each of the target features 22, at least about twice aslarge as the area occupied by each of the target features 22, etc.

In the shown embodiment, the first and second target features 20 and 22are substantially circular features (i.e., are circular to withinreasonable tolerances of fabrication and measurement). In otherembodiments, the first and second target features 20 and 22 may haveother suitable shapes including, for example, elliptical, polygonal,etc.; and may or may not have the same shapes as one another.

The photo-processing utilized to pattern the photoimageable material 12is diagrammatically illustrated with an arrow 24 in FIG. 5 . Suchphoto-processing may utilize an appropriate reticle as described withreference to FIG. 6 .

Specifically, FIG. 6 shows the substrate 14 having the photoimageablematerial 12 thereover. The substrate is oriented relative to aphoto-processing apparatus 26. The apparatus 26 includes a reticle 28, apair of lenses 30 and 32 (i.e., a projection lens and a condenser lens),an aperture 34, and a source 36 which generates electromagneticradiation (with the electromagnetic radiation being diagrammaticallyillustrated with dashed lines 38).

The electromagnetic radiation of FIG. 6 may be referred to as actinicradiation in that it is of a suitable wavelength to cause chemicalchanges within the photoimageable material 12. Such chemical changesrender exposed regions of the photoimageable material to be either moresoluble in developer as compared to unexposed regions (in applicationsin which the photoimageable material 12 is a positive resist), or lesssoluble in developer as compared to unexposed regions (in applicationsin which the photoimageable material 12 is a negative resist).

The reticle 28 comprises a bulk material 29, and comprises patternfeatures (not shown) which are utilized to pattern the openings 20 and22 of FIG. 5 . The pattern features may be, for example, openingsextending into the bulk material 29, opaque regions over the bulkmaterial 29, and/or other configurations. The bulk material 29 maycomprise any suitable composition(s), and in some embodiments maycomprise silicon (e.g., monocrystalline silicon) having suitabletransmissivity.

Difficulties are encountered in attempting to make pattern features(patterning features) suitable for forming both the large openings 20and the small openings 22 (FIG. 5 ) in that the optimal dose of actinicradiation for reticle features associated with the large openings 22 isoften different than that for reticle features associated with the smallopenings 20.

FIG. 7 shows regions 40 and 42 of the reticle 28. The region 40comprises large pattern features 44 configured to pattern large targetfeatures (e.g., the openings 20 of FIG. 5 ) and the region 42 comprisessmall pattern features 46 configured to pattern small target features(e.g., the openings 22 of FIG. 5 ). The features 44 are shown asrectangles and the features 46 are shown as squares. In otherembodiments, the features 44 and 46 may have the same shape as oneanother (e.g., both may be squares, both may be rectangles, etc.). Ifthe features 44 and 46 are both utilized to pattern circular targetfeatures in photoimageable material (as shown in FIG. 5 ), then both ofthe features 44 and 46 may be square.

FIGS. 8 and 9 graphically illustrate optical proximity correction (OPC)threshold levels for the large features 44 and the small features 46(FIG. 7 ). The OPC threshold level for the small feature 46 isillustrated as OPC Threshold-1, and is shown as a dimension X₁; and theOPC threshold level for the large feature 44 is illustrated as OPCThreshold-2, and is shown as a dimension X₂. Notably, X₂ is much lessthan X₁. The OPC threshold level of a pattern feature is inverselycorrelated with the optimal dose appropriate for such pattern feature.Accordingly, the substantial difference between X₁ and X₂ renders itdifficult to appropriately optimize a single dose for both of thepattern features 44 and 46. Instead, a compromise dose is utilized inconventional applications, with the compromise dose being suboptimal forboth of the pattern features 44 and 46.

An aspect of some of the embodiments presented herein is a recognitionthat the optimal dose for the larger pattern feature 44 may be modifiedby changing the configuration of such feature to include an inrigger(i.e., a central region having different opacity than a remainder of thefeature) while still maintaining the ability of the modified patternfeature to generate a desired target feature when actinic radiation ispassed through the modified pattern feature. The inrigger may beconsidered to be an example of a Sub-Resolution Assist Feature (SRAF).

FIG. 10 diagrammatically illustrates the formation of an inrigger 48within the pattern feature 44. Specifically, the left side of FIG. 10shows the original (unmodified) pattern feature 44, together with thegraph showing the OPC threshold level (the dimension X₂) associated withsuch feature. The right side of FIG. 10 shows the feature 44 modified toinclude an inrigger 48, and shows that the modified pattern feature 44has an OPC threshold level (OPC Threshold-3) with a dimension of X₃,where the dimension X₃ is very similar to the dimension X₁ of the OPCthreshold level for the small pattern feature 46 (FIG. 8 ).

In some embodiments, the optimal dose of the actinic radiation for themodified large pattern feature 44 may be within about 5% of the optimaldose of the actinic radiation for the small pattern feature 46. In otherwords, if the small pattern feature has an optimal dose D₁, than themodified large pattern feature 44 may have an optimal dose within arange of from about (D₁−0.5D₁) to about (D₁+0.5D₁). The optimal dosesmay be measured in any suitable units, such as, for example,millijoules/centimeter², (mJ/cm²). In some embodiments, the modifiedlarge pattern feature 44 may have an optimal dose of the actinicradiation within about 1% of the optimal dose for the small patternfeature 46, within about 0.3% of the optimal dose for the small patternfeature, or substantially the same as the optimal dose of the smallpattern feature (where the term “substantially the same” means the sameto within reasonable tolerances of fabrication and measurement).

The inrigger 48 may be considered to correspond to a central region 50of the modified pattern feature 44. An outer region 52 of the patternfeature 44 laterally surrounds the central region 50. The central region50 has a different opacity than the outer region 52. The central regionmay have a lower opacity (higher transmittance, higher transparency)than the outer region, or a higher opacity (lower transmittance, lowertransparency) depending on whether the reticle is utilized forpatterning positive resist or negative resist.

The modified pattern feature 44 may be considered to comprise a firstarea A₁. In the illustrated embodiment of FIG. 10 in which the modifiedpattern feature 44 is a rectangle, such area may be calculated as length(L₁) times width (W₁); i.e., A₁=L₁×W₁. The central region 50 of themodified pattern feature 44 may be considered to comprise a second areaA₂ which may be calculated as L₂×W₂ in the illustrated embodiment. Insome embodiments, the second area A₂ may comprise from about 5% to about95% of the first area A₁, may comprise from about 20% to about 60% ofthe first area A₁, etc.

The configuration (e.g., size, shape, composition, etc.) of theinriggers 48 (central regions 50) of the modified pattern features 44may be determined with any suitable methodology. An example method isdescribed with reference to FIG. 11 .

At an initial step I, at least one simulation of the smaller targetsubassembly (i.e., the small feature patterns 46, which may be referredto as first feature patterns in some embodiments) is run to obtainappropriate sizing of the smaller patterns for imaging quality.

At a subsequent step II, a dose level for the optimal-sized smallertargets of the assembly (i.e., the first feature patterns 46) isdetermined. Such a dose level may be referred to as an optimal dose ofactinic radiation for the first feature patterns 46.

At a subsequent step III, holes (sub-resolution assist features, SRAF)are modeled in polygons of the larger target subassembly (i.e., thelarge feature patterns 44, which may be referred to as second featurepatterns in some embodiments).

At a subsequent step IV, the size of the holes (SRAFs) is varied with asimulation, while the optimal dose for the larger target subassembly(the second features 44) is determined for the simulated features.

At a subsequent step V, the SRAF configuration versus optimal doseascertained at step IV is analyzed (i.e., data points are compared withone another) to determine a relationship between the simulatedconfigurations of the central regions (50 of FIG. 10 ) of the secondpattern features 44 to the optimal dose of actinic radiation suitablefor such second features.

At a final step VI, the SRAF configuration is determined which enablesthe optimal dose of step V to be approximately the same as that of stepII. In other words, the relationship of step V is utilized to ascertaina suitable configuration of the central regions 50 of the second patternfeatures 44 which enables the optimal dose of actinic radiation throughthe second pattern features 44 to be comparable to the optimal dose ofthe actinic radiation through the first pattern features 46. Thecomparable optimal dose through the modified second pattern features 44may be within about 5% of the optimal dose of the actinic radiationthrough the first pattern features 46, within about 1% of the optimaldose through the first pattern features, within about 0.5% of theoptimal dose through the first pattern features, etc. In someembodiments, the optimal dose of the actinic radiation through themodified second pattern features 44 may be substantially identical tothe optimal dose of the actinic radiation through the first patternfeatures 46.

FIG. 12 shows a relationship between an example reticle 28 and apatterned photoimageable material 12 of an assembly 10. The assembly 10of FIG. 12 is identical to that shown at stage “B” of FIG. 5 . Thereticle 28 includes regions 56 a and 56 b which are utilized to patternthe target features 20 of the memory array regions 16 a and 16 b,respectively. The reticle 28 also includes a region 58 which is betweenthe regions 56 a and 56 b, and which is utilized to pattern the targetfeatures 22 within the interconnect region 18.

The regions 56 a and 56 b of the reticle 28 comprise the larger patternfeatures (second pattern features) 44, and the central region 58comprises the smaller pattern features (first pattern features) 46. Thesecond pattern features 44 of the reticle 28 are modified to include theinriggers (central regions) 50, with such central regions beinglaterally surrounded by the outer regions 52. The modified featurepatterns 44 may have a same optimal dose of actinic radiation (or atleast a comparable optimal dose of actinic radiation) to the featurepatterns 46 so that a common optimal dose of actinic radiation may bepassed through all of the features 44 and 46 to pattern the targetfeatures 20 and 22 within the photoimageable material 12 of the assembly10. Such may advantageously improve the patterning of the arrays oftarget features 20 and 22 relative to methods which pass sub-optimaldoses of actinic radiation through the pattern features of a reticle toattempt to form target features analogous to the features 20 and 22 ofthe assembly 10. The patterning described herein may be advantageous forincreasing levels of integration in that the patterning may enable thetarget openings 20 and 22 to be formed with high precision and accuracy.

Notably, the second pattern features 44 are shown as squares in FIG. 12rather than as the rectangles of FIGS. 7 and 10 . Such change in theshape of the pattern features is utilized to emphasize that the patternfeatures may have any suitable shapes, and that the shapes of thepattern features may be tailored for particular applications.

In the FIG. 12 depiction, the columns of second pattern features 44within regions 56 a and 56 b of reticle 28 have the second patternfeatures 44 of alternating columns that are offset relative to thesecond pattern features of adjacent columns. Similarly, as depicted,first pattern features 46 within central region 58 can also be arrangedin columns having first pattern features offset relative to the firstpattern features of adjacent columns. This configuration of first andsecond pattern features can be utilized to produce the pattern of offsettarget features 22 within the interconnect region 18 and offset targetfeatures 20 within array regions 16 a and 16 b of assembly 10 asdepicted. Alternatively, pattern features in one or more of regions 56a, 56 b and 58 of reticle 28 can be aligned in both the row directionand the column direction (not shown) to produce corresponding alignmentof target features in array regions 16 a, 16 b and interconnect region18 of assembly 10. In some embodiments, the pattern of first patternfeatures 46 will match the pattern of second pattern features 44 withrespect to feature alignment (depicted). However, alternate embodimentsmay have one or more of regions 56 a, 56 b and 58 having pattern featurealignment that differs relative to each other to produce a pattern ofdiffering relative target features alignment in regions 16 a, 16 b and18 of the product assembly 10 (e.g. see FIG. 5 ). Alternative featurealignment patterns relative to those specifically depicted arecontemplated.

The second pattern features 44 are larger than the first patternfeatures 46, and may be larger by any suitable amount. In someembodiments, the second pattern features 44 are at least about 50%larger than the first pattern features (i.e., the area of the secondpattern features is at least about 50% larger than the area of the firstpattern features). In some embodiments the second pattern features 44are at least about twice as large as the first pattern features, atleast about 2.5 times as large as the first pattern features, at leastabout three times as large as the first pattern features, etc.

The openings 20 and 22 of the assembly 10 of FIG. 12 may be formed withprocessing analogous to that described above with reference to FIGS. 5and 6 . Specifically, actinic radiation may be passed through thereticle 28 to pattern the actinic radiation, and the patterned actinicradiation may impact the photoimageable material 12 to alter solubilityof the photoimageable material within a developer solution. Regions ofthe photoimageable material 12 exposed to the actinic radiation willbecome either more soluble in the developer solution, or less soluble,depending on whether the photoimageable material is a positive materialor a negative material (e.g., positive resist or a negative resist).Regardless, the actinic radiation which passes through the reticle 28and onto the photoimageable material 12 patterns the first and secondtarget features 20 and 22 within the photoimageable material(specifically, creates a pattern of exposed and unexposed regions withinthe photoimageable material). The first and second target features 20and 22 are developed by utilizing developer solution to remove eitherthe exposed regions of the photoimageable material or the unexposedregions of the photoimageable material, depending on whether thephotoimageable material is a positive material or a negative material.

As discussed above, the central regions 50 of the modified patternfeatures 44 may be more opaque than the outer regions 52 of suchmodified pattern features, or may be less opaque than the outer regions52. FIGS. 13 and 14 illustrate example configurations in which thecentral regions 50 are more opaque than the outer regions 52 (FIG. 13 )and in which the central regions are less opaque than the outer regions52 (FIG. 14 ).

Referring to FIGS. 13 and 13A, the reticle 28 is shown to comprise anopening (window) extending therein which corresponds to the outer region52. Thus, the outer region 52 is less opaque (more transmissive) thanthe central region 50.

Referring to FIGS. 14 and 14A, the reticle 28 is shown to comprise anopaque blocking material 60 corresponding to the outer region 52.Accordingly, the outer region 52 is more opaque (less transmissive) thanthe central region 50.

The embodiments of FIGS. 13 and 14 are example embodiments for forming acentral region 50 to have different opacity than an outer region 52.Other configurations of the central regions 50 and/or outer regions 52may be utilized in other applications.

The example embodiments of the modified pattern features 44 describedabove show the modified pattern features to be four-sided (square orrectangular) and to have the outer regions 52 to be of substantiallyuniform lateral thickness around the central regions 50. FIGS. 15A-15Dillustrate additional example configurations of the modified patternfeatures 44. FIGS. 15A and 15B illustrate embodiments in which the outerregions 52 do not have substantially uniform lateral thicknesses aroundthe central regions 50. In contrast, FIGS. 15C and 15D show embodimentsin which the outer regions 52 do have substantially uniform lateralthicknesses around the central regions 50. FIG. 15D shows an exampleembodiment in which the modified pattern feature 44 is not four-sided.

The assemblies and structures discussed above may be utilized withinintegrated circuits (with the term “integrated circuit” meaning anelectronic circuit supported by a semiconductor substrate); and may beincorporated into electronic systems. Such electronic systems may beused in, for example, memory modules, device drivers, power modules,communication modems, processor modules, and application-specificmodules, and may include multilayer, multichip modules. The electronicsystems may be any of a broad range of systems, such as, for example,cameras, wireless devices, displays, chip sets, set top boxes, games,lighting, vehicles, clocks, televisions, cell phones, personalcomputers, automobiles, industrial control systems, aircraft, etc.

Unless specified otherwise, the various materials, substances,compositions, etc. described herein may be formed with any suitablemethodologies, either now known or yet to be developed, including, forexample, atomic layer deposition (ALD), chemical vapor deposition (CVD),physical vapor deposition (PVD), etc.

The terms “dielectric” and “insulative” may be utilized to describematerials having insulative electrical properties. The terms areconsidered synonymous in this disclosure. The utilization of the term“dielectric” in some instances, and the term “insulative” (or“electrically insulative”) in other instances, may be to providelanguage variation within this disclosure to simplify antecedent basiswithin the claims that follow, and is not utilized to indicate anysignificant chemical or electrical differences.

The terms “electrically connected” and “electrically coupled” may bothbe utilized in this disclosure. The terms are considered synonymous. Theutilization of one term in some instances and the other in otherinstances may be to provide language variation within this disclosure tosimplify antecedent basis within the claims that follow.

The particular orientation of the various embodiments in the drawings isfor illustrative purposes only, and the embodiments may be rotatedrelative to the shown orientations in some applications. Thedescriptions provided herein, and the claims that follow, pertain to anystructures that have the described relationships between variousfeatures, regardless of whether the structures are in the particularorientation of the drawings, or are rotated relative to suchorientation.

The cross-sectional views of the accompanying illustrations only showfeatures within the planes of the cross-sections, and do not showmaterials behind the planes of the cross-sections, unless indicatedotherwise, in order to simplify the drawings.

When a structure is referred to above as being “on”, “adjacent” or“against” another structure, it can be directly on the other structureor intervening structures may also be present. In contrast, when astructure is referred to as being “directly on”, “directly adjacent” or“directly against” another structure, there are no interveningstructures present. The terms “directly under”, “directly over”, etc.,do not indicate direct physical contact (unless expressly statedotherwise), but instead indicate upright alignment.

Structures (e.g., layers, materials, etc.) may be referred to as“extending vertically” to indicate that the structures generally extendupwardly from an underlying base (e.g., substrate). Thevertically-extending structures may extend substantially orthogonallyrelative to an upper surface of the base, or not.

Some embodiments include a photo-processing method. A photoimageablematerial is formed over a substrate. The substrate has a first regionwhere first target features are to be formed and has a second regionwhere second target features are to be formed. The first target featuresare smaller than the second target features. A reticle is configured topattern the first and second target features within the photoimageablematerial. The reticle has first pattern features which pattern the firsttarget features and has second pattern features which pattern the secondtarget features. Each of the second pattern features has a configurationwhich includes a central region and an outer region, with the centralregion being of different opacity than the outer region. The first andsecond pattern features have first and second optimal doses of actinicradiation associated therewith. The configuration of the second patternfeatures balances the second optimal dose of the actinic radiation to bewithin about 5% of the first optimal dose of the actinic radiation. Theactinic radiation is passed through the reticle and onto thephotoimageable material to pattern the first and second target featureswithin the photoimageable material.

Some embodiments include a photo-processing method. Photoimageablematerial is formed over a substrate. A reticle is formed, with thereticle being configured to pattern first and second target featureswithin the photoimageable material. The reticle has first patternfeatures which pattern the first target features and has second patternfeatures which pattern the second target features. The second patternfeatures are larger than the first pattern features. Each of the secondpattern features includes a central region and an outer region laterallysurrounding the central region, with the central region being ofdifferent opacity than the outer region. The central regions are of asuitable configuration so that an optimum dose of actinic radiationthrough the second pattern features is within about 5% of an optimumdose of the actinic radiation through the first pattern features. Thesuitable configuration of the central regions of the second patternfeatures is determined by 1) determining the optimum dose of actinicradiation for the first pattern features, 2) determining a relationshipbetween the configuration of the central regions of the second patternfeatures to the optimum dose of the actinic radiation for the secondpattern features, and 3) utilizing the relationship to ascertain thesuitable configuration of the central regions of the second patternfeatures. The actinic radiation is passed through the reticle and ontothe photoimageable material to pattern the first and second targetfeatures within the photoimageable material.

Some embodiments include a reticle which includes first pattern featuresand second pattern features. A first optimal dose of actinic radiationis associated with the first pattern features and a second optimal doseof the actinic radiation is associated with the second pattern features.The second pattern features are larger than the first pattern features.Each of the second pattern features has a configuration which includes acentral region laterally surrounded by an outer region, with the centralregion being of different opacity than the outer region. Theconfigurations of the second pattern features balance the second optimaldose of the actinic radiation to be within about 5% of the first optimaldose of the actinic radiation.

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

We claim:
 1. A photo-processing method, comprising: formingphotoimageable material over a substrate, the substrate having a firstregion where first target features are to be formed and having a secondregion where second target features are to be formed, the first targetfeatures being smaller than the second target features; forming areticle configured to pattern the first and second target featureswithin the photoimageable material; the reticle having first patternfeatures which pattern the first target features and having secondpattern features which pattern the second target features; each of thesecond pattern features having a configuration which includes a centralregion and an outer region, with the central region being of differentopacity than the outer region; the first and second pattern featureshaving first and second optimal doses of actinic radiation associatedtherewith; the configuration of the second pattern features balancingthe second optimal dose of the actinic radiation to be within about 5%of the first optimal dose of the actinic radiation; and passing theactinic radiation through the reticle and onto the photoimageablematerial to pattern the first and second target features within thephotoimageable material in a single exposure.
 2. The method of claim 1wherein the second optimal dose of the actinic radiation is within about1% of the first optimal dose of the actinic radiation.
 3. The method ofclaim 1 wherein the second optimal dose of the actinic radiation issubstantially equal to the first optimal dose of the actinic radiation.4. The method of claim 1 wherein the central regions of the secondpattern features comprise from about 5% to about 95% of a total area ofthe second pattern features.
 5. The method of claim 1 wherein thecentral regions of the second pattern features comprise from about 20%to about 60% of a total area of the second pattern features.
 6. Themethod of claim 1 wherein the substrate is utilized for a NAND memoryassembly; wherein the second target features are within a memory arrayregion of the NAND memory assembly, and wherein the first targetfeatures are within a second region proximate to the memory arrayregion.
 7. The method of claim 6 wherein the memory array region is oneof two memory array regions of the NAND memory assembly, and wherein thesecond region is between the two memory array regions.
 8. The method ofclaim 1 wherein the photoimageable material is a positive resist.
 9. Themethod of claim 1 wherein the photoimageable material is a negativeresist.
 10. The method of claim 1 wherein the central regions of thesecond pattern features are sub-resolution assist features.
 11. Aphoto-processing method, comprising: forming photoimageable materialover a substrate; forming a reticle configured to pattern first andsecond target features within the photoimageable material; the reticlehaving first pattern features which pattern the first target featuresand having second pattern features which pattern the second targetfeatures; the second pattern features being larger than the firstpattern features; each of the second pattern features including acentral region and an outer region laterally surrounding the centralregion, with the central region being of different opacity than theouter region; the central regions being of a suitable configuration sothat an optimum dose of actinic radiation through the second patternfeatures is within about 5% of an optimum dose of the actinic radiationthrough the first pattern features; the suitable configuration of thecentral regions of the second pattern features being determined by 1)determining the optimum dose of actinic radiation for the first patternfeatures, 2) determining a relationship between the configuration of thecentral regions of the second pattern features to the optimum dose ofthe actinic radiation for the second pattern features, and 3) utilizingthe relationship to ascertain the suitable configuration of the centralregions of the second pattern features; and passing the actinicradiation through the reticle and onto the photoimageable material topattern the first and second target features within the photoimageablematerial in a single exposure.
 12. The method of claim 11 wherein theoptimal dose of the actinic radiation through the second patternfeatures is within about 1% of the optimal dose of the actinic radiationthrough the first pattern features.
 13. The method of claim 11 whereinthe optimal dose of the actinic radiation through the second patternfeatures is within about 0.5% of the optimal dose of the actinicradiation through the first pattern features.
 14. The method of claim 11wherein the optimal dose of the actinic radiation through the secondpattern features is substantially the same as the optimal dose of theactinic radiation through the first pattern features.
 15. The method ofclaim 11 wherein the central regions of the second pattern featurescomprise from about 5% to about 95% of a total area of the secondpattern features.
 16. The method of claim 11 wherein the central regionsof the second pattern features comprise from about 20% to about 60% of atotal area of the second pattern features.
 17. The method of claim 11wherein the first and second pattern features are four-sided features.18. The method of claim 17 wherein the first and second target featuresare substantially circular features.
 19. The method of claim 11 whereinthe central regions of the second pattern features are sub-resolutionassist features.